Study On The Design,Synthesis,and Properties Of Fluorescence Probes Based On Naphthalimide

Hydrogen sulfide(H2S)plays an important role in physical health,plant growth and environment issues.Thus,it has attracted much attention to explore more sensitive and convenient detection methods.Fluorescent probe offers an efficient approach for H2 S detection because of its high sensitivity and convenient operation.At present,most of fluorescence probes only have one recognition site.And the narrow linear detection range limits the application in practical tests.Therefore,it is great significance to design and develop wider linear range probes.In this paper,24 naphthalimide derivatives were designed and selected using quantum chemical calculation.The results of the study showed that the HOMO-LUMO energy gaps were lower(2.87-2.88 e V)when the 4-position of naphthalimide derivatives were substituted with –OH.The maximum absorption and fluorescence peaks were 450 nm and 550 nm,respectively.And the Stokes-shift values of 4-hydroxyl-1,8-naphthalimide derivatives were 99.67-101.95 nm.In overall,4-hydroxyl-1,8-naphthalimide derivatives were believed as ideal fluorophores due to the long absorption and emission wavelengths,lower HOMO-LUMO gap and lower fluorescence self-quenching effect.In this paper,four fluorescence-enhanced probes were designed and synthesized for detection of H2 S based on 4-hydroxyl-1,8-naphthalimide.The experiments including UV-absorption spectra,fluorescence spectra,fluorescence quantum yield,detection limit experiment,interfence and competitive ions experiment,p H effect experiment were carried to study the selectivity and sensitivity of the probes.The research showed that NTE-1,NTE-2 and NTE-3 displayed large red-shift(excess 100 nm)in absorption spectral and more than 30-fold fluorescence enhancement in response to H2 S in the p H range of 5-8.The linear range of dual site probe(NTE-3)was 0-40 μmol/L,which extended the quantitative detection range of H2 S by fluorescence probe.The color change of NTE-4 can be observed from colorless to pink by naked eye after the addition of H2 S.The PET response mechanisms of probes were further studied by analyzing the distributions of molecular orbital.